1. Field of the Invention
The present invention relates in general to a method for treating autism and, more particularly, to a method for treating autism via administering an effective amount of a NMDA-receptor antagonist or a pharmaceutically acceptable salt thereof.
2. Background Art
Autism is a complex developmental disability that interferes with, among other things, the normal development of the brain in the areas of social interaction and communication skills. It typically appears during the first three years of life and is the result of a neurological disorder which affects the functioning of the brain. Typically, autistic children and adults have difficulties in verbal and non-verbal communication, social interactions, and leisure or play activities.
According to the Autism Society of America (hereinafter the “ASA”), autism is generally characterized as one of five disorders coming under the umbrella of Pervasive Developmental Disorders (PDD), a category of neurological disorders characterized by severe and pervasive impairment in several areas of development, including social interaction and communications skills (DSM-IV-TR). The five disorders under PDD are Autistic Disorder, Asperger's Disorder, Childhood Disintegrative Disorder (CDD), Rett's Disorder, and PDD-Not Otherwise Specified (PDD-NOS). Specific diagnostic criteria for each of these disorders can be found in the Diagnostic & Statistical Manual of Mental Disorders (DSM-IV-TR) as distributed by the American Psychiatric Association (APA).
The most common of the Pervasive Developmental Disorders, autism affects an estimated 1 in approximately 200 births. Indeed, as of 2003-2004, as many as 1.5 million Americans are believed to have some form of autism. Such a number is on the rise inasmuch as, based on statistics from the U.S. Department of Education and other governmental agencies, autism is growing at a rate of 10-17 percent per year. At these rates, the ASA estimates that the prevalence of autism could easily reach 4 million Americans in the next decade.
The overall incidence of autism is, for the most part, globally consistent. Indeed, autism knows no racial, ethnic, or social boundaries, and family income, lifestyle, and educational levels do not affect the chance of autism's occurrence. However, it has been found to be four times more prevalent in boys than girls.
Since being first described by Dr. Leo Kanner in 1943, the understanding of autism has grown tremendously. However, the general public, and even many professionals in the medical, educational, and vocational fields, remain unaware of the effects of the disability and how to most effectively work with individuals having the disability. For example, autistic individuals may exhibit both positive and negative responses to their environment. Though some may find it surprising, many children and adults with autism may make eye contact, show affection, smile and laugh, and demonstrate a variety of other emotions, although in varying degrees.
Although autism is defined by a certain set of behaviors, it is a spectrum disorder in that its symptoms and characteristics can be present in a wide variety of combinations, from mild to severe. Therefore, autistic children and adults can exhibit any combination of the behaviors in any degree of severity. Two individuals, both with the same diagnosis, may have varying skills and display very different actions.
Indeed, every person with autism is an individual, and like all individuals, each has a unique personality and combination of characteristics. Those only mildly affected may exhibit slight delays in language or communication and may face greater challenges in social interactions. For example, one may have difficulty initiating and/or maintaining a conversation. Communication by autistic children or adults is often displayed as talking at others (for example, a monologue on a favorite subject that continues despite attempts by others to interject comments).
Autism requires those affected by it to process and respond to information in unique ways. At times, aggressive and/or self-injurious behavior may exist. The following traits, as identified by the ASA, may also be present in persons with autism: Insistence on sameness or resistance to change; Difficulty in expressing needs; (i.e. uses gestures or pointing instead of words); Repeating words or phrases in place of normal, responsive language; Laughing, crying, showing distress for reasons not apparent to others; Prefers to be alone or aloof manner; Tantrums; Difficulty in mixing with others; May not want to cuddle or be cuddled; Little or no eye contact; Unresponsive to normal teaching methods; Sustained odd play; Spins objects; Inappropriate attachments to objects; Apparent over-sensitivity or under-sensitivity to pain; No real fears of danger; Noticeable physical over-activity or extreme under-activity; Uneven gross/fine motor skills; and/or Not responsive to verbal cues (i.e. acts as if deaf although hearing tests in normal range).
For most people, our senses help us to understand what we are experiencing. For example, our senses of touch, smell, sound, and taste collaborate to give us a full experience of eating a ripe apple: the feel of the smooth skin as we pick it up, its sweet smell as we move it to our mouth, the crunch of the fruit being bitten into, and the juices running down our face as we enjoy the bite. For individuals with autism, however, sensory integration problems are common. In particular, their senses may be either over- or under-active. The fuzz of a kiwi may actually be experienced as painful; a sweet, fruity smell may cause a gagging reflex. Some children or adults with autism are particularly sensitive to sound, so that even the most ordinary daily noises are painful. Many professionals feel that some of the typical autism behaviors are actually a result of sensory integration difficulties.
Although there is no known single known cause for autism, it is generally accepted that it is caused by abnormalities in brain structure or function. The shape and structure of the brain in autistic versus non-autistic children show differences when brain scans are viewed. Currently the link between heredity, genetics and medical problems are being investigated by researchers, as well as a number of other theories. The theory of a genetic basis of the disorder is supported by the fact that, in many families, there appears to be a pattern of autism or related disabilities. While no one gene has been identified as causing autism, researchers are searching for irregular segments of genetic code that autistic children may have inherited. While researchers have not yet identified a single “trigger” that causes autism to develop, it also appears that some children are born with a susceptibility to autism.
Other researchers are investigating the possibility that under certain conditions, a cluster of unstable genes may interfere with brain development resulting in autism. Still other researchers are investigating problems during pregnancy or delivery as well as environmental factors such as viral infections, metabolic imbalances, and exposure to environmental chemicals.
According to the ASA, autism tends to occur more frequently than expected among individuals who have certain medical conditions, including Fragile X syndrome, tuberous sclerosis, congenital rubella syndrome, and untreated phenylketonuria (PKU). Some harmful substances ingested during pregnancy also have been associated with an increased risk of autism. Early in 2002, The Agency for Toxic Substances and Disease Registry (ATSDR) prepared a literature review of hazardous chemical exposures and autism found no compelling evidence for an association; however, there was very limited research and more needs to be done.
Whatever the cause, parents can rest assured that autism is not caused by bad parenting. Children with autism and PDD are either born with the disorder or with the potential to develop it. No known psychological factors in the development of the child have been shown to cause autism. Furthermore, autism is not a mental illness; autistic children are not unruly kids who choose not to behave.
Notwithstanding the foregoing, and to the best of Applicant's knowledge, there is no cure for autism. There are, however, a number of medications, developed for other conditions, which have been found to be somewhat helpful in treating a limited number of the symptoms and behaviors frequently found in individuals with autism, such as hyperactivity, impulsivity, attention difficulties, and anxiety. Examples of medications used to treat symptoms associated with autism include: Serotonin re-uptake inhibitors (e.g. clomipramine (Anafranil), fluvoxamine (Luvox) and fluoxetine (Prozac)) which have been effective in treating depression, obsessive-compulsive behaviors, and anxiety that are sometimes present in autism. Studies have shown that they may reduce the frequency and intensity of repetitive behaviors, and may decrease irritability, tantrums and aggressive behavior. Some children have shown improvements in eye contact and responsiveness. Other drugs, such as Elavil, Wellbutrin, Valium, Ativan and Xanax, require more studies to be done but may have a role in reducing behavioral symptoms.
Over the past 35 years, the most widely studied psychopharmacologic agents in autism have been anti-psychotic medications. Originally developed for treating schizophrenia, these drugs have been found to decrease hyperactivity, stereotypic behaviors, withdrawal and aggression in autistic children. Four that have been approved by the FDA are clozapine (Clozaril), risperidone (Risperdal), olanzapine (Zyprexa) and quetiapine (Seroquel). However, only risperidone has been investigated in a controlled study of adults with autism. Unfortunately, like the antidepressants, these drugs all have adverse side effects, including, but not limited to, sedation.
Stimulants, such as Ritalin, Adderall, and Dexedine, used to treat hyperactivity in children with ADHD have also been prescribed for children with autism. Although few studies have been done, they may increase focus, and decrease impulsivity and hyperactivity in autism, particularly in higher-functioning children. Unfortunately, adverse behavioral side effects are often observed.
While many of the above-identified medications do appear to be somewhat helpful in treating a limited number of the symptoms and behaviors frequently found in individuals with autism, a wide variety of side effects are associated with such medications.
It has now been surprisingly discovered that administering an effective amount of a NMDA-receptor antagonist or a pharmaceutically acceptable salt thereof appears to substantially improve frontal executive functions associated with autistic symptoms, including, but not limited to, speech expression and decreased perseveration. Furthermore, administering such a NMDA-receptor antagonist or a pharmaceutically acceptable salt thereof has not been shown to cause side effects associated with medications previously used to treat the symptoms of autism.
It is therefore an object of the present invention, to provide a method for treating autism via administering an effective amount of a NMDA-receptor antagonist or a pharmaceutically acceptable salt thereof.